Vertical shaft internal combustion engines are becoming increasingly popular for use in lawn tractors. Their vertical shaft drives grass cutting blades without the use of a costly transmission. Consumer preferences, however, currently dictate lawn tractors with a low hood line. In a vertical shaft engine, this requires a short compact configuration. Even in larger tractors, such as those requiring an engine having 16 hp-35 hp, a low hood line is important to consumers. These larger engines, generate a significant amount of heat during operation and are typically liquid cooled. Liquid cooled vertical shaft engine are not easily shortened because of the necessity of a radiator to cool the liquid cooling the engine.
Liquid cooled engines have cooling circuits which circulates liquid coolant to maintain a desired engine temperature. These cooling circuits have coolant bottles for receiving heated coolant which expands beyond the volume capacity of the cooling circuit. When the coolant in the cooling circuit cools, it contracts, drawing coolant from the bottle back into the cooling circuit. The coolant bottles, are generally located proximate the radiator, and attached to an external portion of the engine increasing the overall external engine dimension.